Compressors used in refrigeration, air conditioning and heat pump systems, hereinafter referred simply as HVAC systems, are normally mounted in an associated unit that houses such a compressor using a mounting plate. The HVAC system normally includes an indoor unit, an outdoor unit and conduit connecting the indoor unit and the outdoor unit. The indoor unit includes a heat exchanger and is designed to distribute conditioned air through the interior of a structure, while the outdoor unit is enclosed in a cabinet that includes a heat exchanger, which exchanges heat with the atmosphere. Refrigerant cycles through the conduit between the heat exchangers. When strictly used as an air conditioner, the refrigerant cools the interior of a structure while removing heat and exchanging it with the atmosphere through the outdoor unit. However, when used as a heat pump, the HVAC system can additionally be used to draw heat from the atmosphere through the heat exchanger in the outdoor unit and transfer and distribute heat to the interior of the structure through the indoor unit. The compressor is usually enclosed within and mounted to the cabinet of the outdoor unit. The mounting plate desirably should reduce the vibrations and resulting noise caused by compressor operation.
Several different types of compressors can be used in HVAC systems. These typically include reciprocating compressors, scroll compressors and rotary compressors, although other types of compressors may be used. Each of these compressors operates in a different manner, and therefore produces different vibrations. Even within a particular type or family of compressors, different sizes within the compressor type or family may produce different vibrations. For example, a large twin piston, reciprocating compressor can produce different characteristic vibrations than a smaller single piston, reciprocating compressor.
It is desirable to reduce the vibration transmitted by the compressor to the cabinet into which it is installed. For many HVAC systems, the compressor is installed in a cabinet referred to as an outdoor unit of the HVAC system, which outdoor unit may be installed on a roof or adjacent to the structure or building. The vibration can be reduced or dampened by the type of mounting used to mount the compressor in the cabinet.
In the past, the compressor has been mounted to the unit using a metal plate, which has provided very little damping of the compressor vibration, the metal plate being a poor damper and a very effective transmitter of the vibration. Different solutions have been used to address vibration damping of compressors mounted within units for different applications. In U.S. Pat. No. 6,354,558 B1, elastomeric grommets are positioned between the feet of the compressor and the base pan upon which it is mounted. The grommets support the weight of the compressor and are radially spaced from its center of gravity to prevent it from tipping. The grommets serve to vibrationally and acoustically isolate the compressor from its support in the unit.
Other solutions to the problem of compressor vibration include the use of internal dampers to reduce the vibration of the compressor moving parts, such as set forth in U.S. Pat. No. 5,252,038. In this approach, springs are mounted on resilient snubbers to dampen the vibration within the compressor housing. U.S. Pat. No. 4,964,786 ('786 patent) and U.S. Pat. No. 4,964,609 ('609 patent) utilize a resilient thermoplastic mounting boot having an upwardly extending rim that corresponds to an annular groove in the compressor, while U.S. Pat. No. 4,917,581 includes an upstanding sidewall that engages, frictionally, the circumferential wall of the compressor. In the '786 patent, the boot is adhesively attached to the compressor, while in the '709 patent, the compressor is frictionally engaged to the boot. The boot is also adhesively attached to a horizontal support surface in the '786 patent, whereas in the '709 patent, the compressor is attached to a horizontal support via bolts. These schemes provide sound and vibration suppression within the appliance cabinet while eliminating the need for hardware welded to the exterior of the compressor housing.